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rust-windowing / winit

Window handling library in pure Rust
https://docs.rs/winit/
Apache License 2.0
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Documentation doesn't explain how to create an ActiveEventLoop #3877

Open Calandiel opened 3 months ago

Calandiel commented 3 months ago

To quote from https://docs.rs/winit/latest/winit/index.html

Before you can create a Window, you first need to build an EventLoop. This is done with the EventLoop::new() function.

use winit::event_loop::EventLoop;
let event_loop = EventLoop::new().unwrap();

Then you create a Window with create_window

This doesn't work because the suggested next step requires a different type. While there are examples in repo, they're all large and bespoke which encourages using the library as a blackbox. Some other users had similar issues: https://github.com/rust-windowing/winit/discussions/3662

Personally, reading the docs, I'm still not sure if it's even possible to use the library without having it hijack the execution flow from the hosting applications thread.

My impression is that it isn't (as per comments on run_app regarding handling of iOS) and you're expected to provide an Application type. If that is the case, it may be worth clarifying in the docs too as the next step isn't to create a Window with create_window but to implement.

daxpedda commented 3 months ago

Personally, reading the docs, I'm still not sure if it's even possible to use the library without having it hijack the execution flow from the hosting applications thread.

My impression is that it isn't (as per comments on run_app regarding handling of iOS) and you're expected to provide an Application type.

Indeed.

However there is run_on_demand and pump_events, but not for iOS.

The documentation is outdated in this regard! So thank you for filing the issue, I'm planning to do a documentation overhaul before the next release.

kchibisov commented 3 months ago

I'd note that ios itself works by transferring all the control flow and you can not even return, because you must transfer the control flow and you have the same looking callbacks from ios as what you have with winit, so it's not possible on a platform level, and not just winit limitation in ios case.

madsmtm commented 3 months ago

I'd note that ios itself works by transferring all the control flow

Indeed. I recently looked at SDL, seems like even they instead run the user's pump_events-like code on a separate thread. SDL3 has recently also fixed this by providing (effectively) closures that gets run on each event.